Support member assembly for conductive contactor

ABSTRACT

Provided is a support member assembly suitable for use in a contact probe head comprising a support member formed with a plurality of holder holes for supporting conductive contact members in a mutually parallel relationship, and a reinforcing member integrally formed with the support member and extending in a part of the support member devoid of any holder holes. The reinforcing member increases the overall mechanical strength of the support member assembly, and prevents the thermal deformation of the support member. Because the holder holes are formed in the support member made of material suitable for forming holes, such as plastic material, the holder holes can be formed at high precision and at low cost.

TECHNICAL FIELD

The present invention generally relates to a support arrangement forconductive contact members for contact probe heads, electric sockets andother applications, and in particular relates to a support memberassembly for conductive contact members for contact probe heads suitablefor burn-in tests of semiconductor related components.

BACKGROUND OF THE INVENTION

In recent years, burn-in tests are routinely conducted as a part of atest process for semiconductor related components, and in such a test avoltage is applied to an object for a prolonged period of time (from fewhours to tens of hours) at an elevated temperature (approximately 150°C). It is more and more preferred to conduct such a test on a waferlevel (8 inch or 200 mm wafer) rather than on a package level so thatthe yield factor may be improved. At any event, when applying a contactprobe head for simultaneously accessing a large number of points duringa burn-in test, the heat resistance and thermal expansion of the supportmember for electric contact members are important factors that need tobe taken into account.

The conductive contact member is desired to be able to accommodatevariations in the height of the corresponding electrode on the wafer byresiliently engaging such an electrode. Such an example is illustratedin FIG. 10. Referring to FIG. 10, a plurality of stepped holder holes 2are passed across the thickness of a support member 21 in the form of aplate member. A small diameter section 2 a of each holder hole 2slidably receives a conductive needle member 23, and a large diametersection 2 b of the holder hole 2 receives a conductive coil spring 24.The conductive needle member 23 includes a radial flange 23 a which isreceived in the large diameter section 2 b, and is resiliently urged bythe coil spring 24 having one end wound around a stem portion 23 bextending from the flange 23 a. The other end of the coil spring 24resiliently engages a corresponding terminal 25 a of a circuit board 25which is placed over the support member 21. The terminal 25 a isconnected to an electric circuit of a tester not shown in the drawing.

A number of such conductive needle members 23 are arranged in parallelto each other in the support member 21 as illustrated in FIG. 10 to forma contact probe head capable of accessing a plurality of points at thesame time. An electric test is conducted by pushing such conductiveneedle members 23 onto the electrodes 26 a of a wafer 26 (object to betested) in a resilient manner.

To allow a plurality of electrodes 26 a on the wafer 26 to be accessedat the same time as mentioned above, it is necessary to arrange in thesupport member 21 a same number of conductive contact members 23 as thenumber of the electrodes 26 a on the wafer 26, and the support member 21is required to be formed with a large number of holder holes 2 in aprecise manner. Furthermore, because an elevated temperature in theorder of 120 to 150° C. is maintained for tens of hours in a burn-intest, the contact probe head is required to be provided with acorresponding heat resistance and low thermal coefficient.

The materials having a heat resistance and thermal coefficientcomparable to that of silicon serving as the material for a waferinclude ceramics, glass and low thermal expansion alloys such as invaras well as silicon. However, machining a silicon member is atime-consuming process, and silicon requires electric insulation.Ceramics are known to be difficult to machine. Glass involvessignificant dimensional errors when machining, and this results in apoor yield factor. A low thermal expansion alloy is difficult tomachine, and requires electric insulation. Therefore, when suchmaterials are selected for the support member of a contact probe head,the production efficiency is low, and the production cost is high.

Plastic material suited for precision machining is suitable as thematerial for the support member. However, in a contact probe head havinga large number of conductive contact members arranged in a supportmember at a high density, the pressure produced from such a large numberof conductive contact members may cause a warping of the support member.The thermal expansion may cause positional errors of the conductivecontact members (conductive needle members), and the access point ofeach conductive contact member may unacceptably offset from the desiredpoint.

BRIEF SUMMARY OF THE INVENTION

In view of such problems of the prior art, a primary object of thepresent invention is to provide a support member assembly for supportingconductive contact members in a contact probe head or the like whichallows small holder holes to be formed at high density and at highprecision, and demonstrates a high mechanical rigidity.

A second object of the present invention is to provide a support memberassembly for supporting conductive contact members in a contact probehead or the like which allows small holder holes to be formed at highdensity and at high precision, and undergoes a thermal expansion in acontrolled manner.

A third object of the present invention is to provide such a supportmember assembly for supporting conductive contact members in a contactprobe head or the like which is both economical and easy to manufacture.

According to the present invention, such objects can be accomplished byproviding a support member assembly suitable for use in a contact probehead or the like for contacting an object to be contacted, comprising: asupport member formed with a plurality of holder holes for supportingconductive contact members in a mutually parallel relationship, thesupport member being made of material suitable for forming such holderholes; and a reinforcing member integrally formed with the supportmember and extending in a part of the support member devoid of anyholder holes.

Thus, because the holder holes for supporting conductive contact memberscan be formed at high precision by forming the holder from materialsuitable for forming such holes such as plastic material, the holderholes may be arranged in fine pitches at high precision to the extentthat is required in wafer level tests. Even when plastic material suchas PPS, LCP, PES and PEI which may by itself not be provided with thedesired mechanical property for a support member is used, thereinforcing member ensures the overall mechanical strength of thesupport member assembly. The reinforcing member may consist of anymaterials having desired mechanical properties such as mechanicalstrength and rigidity, and such materials include metallic materials,glass, ceramics and silicon. When a low thermal expansion coefficientmaterial having a lower thermal expansion coefficient such as invar andKovar™ is used, the thermal deformation of the support member during aburn-in test can be avoided. Also, as compared to the case where thesupport member is made of a single material such as low thermalexpansion coefficient alloy such as invar, ceramics, glass or silicon,and the holder holes are formed in such material, the manufacturing costcan be significantly reduced.

The reinforcing member preferably divides the support member into aplurality of regions each of which is formed with a plurality of holderholes. Thus, an optimum mode of reinforcement can be achieved for thegiven layout of the conductive contact members. If the reinforcingmember consists of an annular member extending along an outer peripheralpart of the support member, a particularly simple and economicalreinforcement can be accomplished. If the layout of the conductivecontact members permits, the reinforcing member may be arranged for amaximum reinforcement by dividing the support member into a plurality ofregions each of which is formed with a single holder hole.

According to a preferred embodiment of the present invention, thereinforcing member consists of a low thermal expansion metallic membersuch as invar and Kovar™, and the support member is made of plasticmaterial which is suitable for drilling or otherwise forming holderholes. In such a case, the reinforcing member may be insert molded inthe support member. Alternatively, the reinforcing member may beexternally attached to the support member.

The object to be tested such as a semiconductor chip is provided withcontact pads that need to be accurately contacted by the conductivecontact members, but such pads are not designed for simplifying such aprocess. It is therefore essential to ensure the positional accuracy ofthe conductive contact members contacting the object to be tested. Inthe case of a support member assembly having a layered structure, it canbe accomplished by using a support member in the form of a reinforcedplate member only in the outer layer thereof facing the object to thetested. If the relay board on the side of the test fixture is designedso as to be tolerant on the positional accuracy of the conductivecontact members, the outer layer facing the relay board may not berequired to be reinforced. However, if necessary, it is possible toreinforce both the outer layers, and even the intermediate layers may bereinforced.

According to yet another embodiment of the present invention, aparticularly economical and simple arrangement is provided by using apair of annular members which clamp the plate members of the assemblytogether along an outer periphery thereof for reinforcement.

BRIEF DESCRIPTION OF THE DRAWINGS

Now the present invention is described in the following with referenceto the appended drawings, in which:

FIG. 1 is a plan view of a support member assembly for use in a contactprobe head according to the present invention;

FIG. 2 is a fragmentary sectional view taken along line II-II of FIG. 1;

FIG. 3 is a view similar to FIG. 1 showing a second embodiment of thepresent invention;

FIG. 4 is a fragmentary sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is an enlarged fragmentary sectional view showing a thirdembodiment of the present invention;

FIG. 6 is an enlarged sectional side view of a contact probe headincluding a support member assembly given as a fourth embodiment of thepresent invention;

FIG. 7 is a view similar to FIG. 2 showing a fifth embodiment of thepresent invention;

FIG. 8 is a view similar to FIG. 2 showing a sixth embodiment of thepresent invention;

FIG. 9 is a view similar to FIG. 2 showing a seventh embodiment of thepresent invention; and

FIG. 10 is a sectional side view, partly in section, showing aconventional support member assembly along with conductive contactmembers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a plan view of a support member 1 for supporting conductivecontact members in a contact probe head embodying the present invention,and FIG. 2 is a sectional view taken along line II-II of FIG. 1. Theconductive contact members in the form of needle members and coilsprings which are to be combined with the support member 1 are omittedin these drawings as they are conventional by themselves. The presentinvention is applicable also to cases where the coil springsadditionally serve as conductive contact members.

When the object to be tested consists of an 8-inch wafer, the supportmember 1 may consist of a disk having a diameter of approximately 8inches (approximately 200 mm) as shown in the drawings. The thickness ofthe support member 1 is typically in the order of 0.5 to 1.5 mm, but mayalso be in the order of 0.1 to 0.2 mm when a laminated structure isemployed. An 8-inch wafer typically contains from tens to hundreds ofsemiconductor chips formed therein. This support member 1 is alsoapplicable to contact probe heads intended for larger objects such as12-inch wafers. A 12-inch wafer typically contains thousands ofsemiconductor chips formed therein.

Referring to FIGS. 1 and 2, the support member 1 is formed with aplurality of groups of holder holes 2 for supporting conductive contactmembers so as to correspond to the electrodes of a plurality of chipsformed on a wafer not shown in the drawings. The shape of each holderhole 2 may be any one of per se known shapes for holder holes. As bestshown in FIG. 1, the holder holes 2 are arranged into a number of groupseach corresponding to a single chip, and a reinforcing member 3 isburied within the support member 1 in an integral manner.

The reinforcing member 3 extends to a vicinity of the outer periphery ofthe support member 1 generally in the shape of a disk, and is providedwith a plurality of rectangular openings 3 a each for accommodating acorresponding group of the holder holes 2. Thus, the reinforcing member3 occupies a part of the support member 1 where the holder holes 2 areabsent or sparsely distributed.

In this support member assembly for a contact probe head, thereinforcing member 3 is formed as a plate member made of heat resistantand low thermal expansion alloy, such as invar and Kovar™, which isformed with the openings 3 a corresponding to individual chips byetching, laser machining, stamp forming or other mechanical metalworking process, and is integrally buried in the support member made ofplastic material by insert molding in the illustrated embodiment. Thus,the support member 1 is integrally incorporated with the reinforcingmember 3. Because the area of the support member 1 corresponding to eachopening 3 a of the reinforcing member 3 is filled with the plasticmaterial, the holder holes 2 can be formed both easily and accurately,and the reinforcing member 3 prevents the thermal deformation of thesupport member 1.

A second embodiment of the present invention is now described in thefollowing with reference to FIGS. 3 and 4. In these drawings, the partscorresponding to those of the previous embodiment are denoted with likenumerals, and description of such parts are omitted. In the secondembodiment, an annular reinforcing member 4 made of invar extendscircumferentially in a continuous manner, and is concentrically buriedin the support member 1 along an outer peripheral part thereof. Theannular member 4, although it consists of a simple ring, can adequatelyincrease the overall mechanical strength of the support member 1 to theextent necessary to prevent an excessive thermal deformation of thesupport member 1 during a burn-in test. The simplification of the shapeof the reinforcing member 4 contributes to the reduction in themanufacturing cost.

According to the present invention, the shape of the reinforcing memberis not limited to those illustrated above. If there is no spatiallimitation, the reinforcing member 6 may be provided with a plurality ofopenings 6 a each corresponding to a single holder hole 5 as shown inFIG. 5. According to a support member 1 having such a reinforcing member6 buried therein, because the part surrounding each holder hole 5 isindividually reinforced, the mechanical strength can be improved evenfurther, and this in turn leads to an improved heat resistance and lowerthermal expansion coefficient.

Also, the holder holes 5 formed in the support member 1 are not limitedto the stepped holes illustrated above, but may also consist of straightholes as shown in FIG. 5 depending on the structure of the conductivecontact members. Such an example is described in the following withreference to FIG. 6. The contact probe head 7 illustrated in FIG. 6 hasa laminated structure including a reinforced outer layer according tothe present invention. A support member 1 incorporated with areinforcing member 3 similar to that of the embodiment illustrated inFIGS. 1 and 2 is formed with holder holes 5 consisting of straightholes, and is used as an outer layer opposing the object to be accessedin a support member assembly 7a of the contact probe head 7 by combiningit with plastic plate members 8 and 9 which may not be provided with anyreinforcing member, for instance. In the illustrated embodiment, a pairof plate members 8 and 9 are used in combination with the support member1, but the support member 1 may be combined with any number of platemembers in the laminated structure.

In this contact probe head 7, the stem portion of each of a plurality ofper se known conductive needle members 11 is slidably received in acorresponding one of the holder holes 5. The plate member 8 serving asan intermediate layer of the support member assembly 7 a is formed withenlarged through holes 8 a which align with the corresponding holderholes 5. The plate member 9 serving as the outer layer facing away fromthe object to be accessed is formed with stepped holes 9 a which alignwith the corresponding holder holes 5. Each straight through hole 8 areceives an enlarged part of the corresponding conductive needle member11 and a coil spring 12, and each stepped hole 9 a receives a part ofthe corresponding coil spring 12 and a conductive needle member 13 forengaging a pad on a relay board not shown in the drawings. The opposingconductive needle members 11 and 13 are resiliently urged away from eachother by the coil spring 12, and are prevented from being dislodged fromthe holder hole 5 by their enlarged portions engaged by annularshoulders defined in the support member assembly 7 a.

The support member 1 is arranged as the outer layer opposing the objectto be contacted (such as the electrodes 26 a in the prior art of FIG.10) in the foregoing embodiment, and this ensures the positionalaccuracy of each conductive contact member with respect to the object tobe accessed owing to the presence of the reinforcing member 3. The otherouter layer or the lower layer is not incorporated with a reinforcingmember. However, because the lower layer opposes a relay board or thelike which is provided with contact pads for the convenience of contactas opposed to such objects to be contacted as semiconductor deviceswhich are designed without such considerations, the lower layer 9 a maynot be required to be reinforced. As can be readily appreciated, ifdesired, the lower layer and/or intermediate layer may be reinforced. Atany even, such a reinforcing member may consist of a member having asmall thickness which can be worked into fine shapes at low cost byetching or the like.

Although the reinforcing member was buried in the support member in eachof the foregoing embodiments, the reinforcing member is only required tobe integrally attached to the support member, and is not necessarilyrequired to be buried in the support member. An alternate embodiment ofthe mounting structure for the reinforcing member is shown in FIG. 7.Referring to FIG. 7, an annular reinforcing member 3 such as the oneillustrated in FIGS. 3 and 4 is used. After holder holes 2 and anannular groove 10 for mounting the reinforcing member 3 are formed inthe support member 1, the reinforcing member 3 is fitted into theannular groove 10, and the reinforcing member 3 is integrally attachedto the support member 1 by using a bonding agent, threaded bolts orother securing means. If desired, to achieve an even higher level ofprecision, the holder holes 2 may be formed after the reinforcing member3 is incorporated in the support member 1. If necessary, the annulargroove 10 may be filled with resin material or the like. This embodimentprovides similar advantages as those of the previous embodiments.

FIG. 8 shows yet another embodiment of the present invention. First ofall, a pair of support members 1 a and 1 b made of plastic material forforming holder holes are prepared. The outer peripheral par of eachsupport member 1 a and 1 b is formed with an annular shoulder which maybe formed at the time of molding the support member or may be machinedafter it has been molded. Holder holes 2 are formed in each of thesupport members 1 a and 1 b, and with the two support members 1 a and 1b placed one over the other, a pair of annular reinforcing members 3 aand 3 b adapted to engage the annular shoulders and made of suchmaterial as invar are fitted on the outer peripheral part of the supportmembers 1 a and 1 b. Then, the support members are firmly joined to eachother by using a suitable number of threaded bolts 14 passed through thereinforcing members 3 a and 3 b and nuts 15 threaded with the threadedbolts 14. The annular reinforcing members 3 a and 3 b not only thus jointhe two support members to each other but also increases the mechanicalrigidity of the support members 1 a and 1 b, and controls thedeformation thereof due to thermal expansion.

FIG. 9 shows yet another embodiment of the present invention. In thisembodiment, the support member 1 consists of a single plate member madeof plastic material suitable for forming holes, and the holder holed 2consist of stepped holed. The outer peripheral part of the supportmember 1 is formed with an annular shoulder, and an annular reinforcingmember 3 made of material such as invar having a complementary shape tothe annular shoulder is fitted on the outer peripheral part of thesupport member 1. Thus, the support member 1 when combined with theannular reinforcing member 3 defines a substantially perfect disk as awhole. The annular reinforcing member 3 is formed with a plurality ofmounting holes 16 and corresponding holes aligning there to are formedin the corresponding parts of the outer periphery of the support member1. The relay board 25 which is to be laid over the surface of thesupport member 1 corresponding to the large diameter ends of the holderholes 2 is provided with threaded holes 17 corresponding to the mountingholes 16. Therefore, when the threaded bolts 14 are passed through theannular reinforcing member 3 which is fitted on the support member 1,and threaded into the corresponding threaded holes 17, the reinforcingmember 3 can be attached to the relay board 25 jointly with the supportmember 1. Each mounting hole 16 of the annular reinforcing member 3 isprovided with a large diameter end adapted to receive the head of thethreaded bolt 14 so that the head of the threaded bolt 14 would notproject from the profile of the assembly.

In any of the foregoing embodiments, the plastic material forming thepart in which the holder holes are formed may consist of any plasticmaterial as long as it is resistant to heat of temperature in the orderof 150° C. in the case of a burn-in test, and has a relative low thermalexpansion coefficient. It should be also suitable for precise holedrilling so as to provide a maximum freedom of design. For instance, theholder holes are not limited to the stepped holes and straight holes,but may also consist of tapered holes or holes of any other shape so asto permit the use of various forms of conductive contact members inaddition to the combination of needle members and coil springs shown inthe illustrated embodiments. The plastic material may also beadditionally reinforced by glass fibers, graphite fibers or othermaterial.

The contact probe head using the support member assembly of the presentinvention is suitable not only for burn-in tests but also for otherapplications where heat resistance is required. Particularly suitableapplications include the use as burn-in sockets, contact probe heads forMPU devices which involve electrode pads arranged at a high density, andcontact probe heads for MCM (multi chip module) devices having aplurality of groups of electrode pads arranged at a high density where ahigh mechanical strength is required.

Although the present invention has been described in terms of preferredembodiments thereof, it is obvious to a person skilled in the art thatvarious alterations and modifications are possible without departingfrom the scope of the present invention which is set forth in theappended claims.

Industrial Applicability

Thus, according to the present invention, the reinforcing memberincreases the overall mechanical strength of the support memberassembly, and when it is made of a heat resistant and low thermalcoefficient material, prevents the thermal deformation of the supportmember. Because the holder holes are formed in the support member madeof material suitable for forming holes, such as plastic material, theholder holes can be formed at high precision and at low cost. Thesupport member assembly according to the present invention is thusparticularly suitable for use in contact probe heads for burn-in tests,and contributes to the reduction in the cost of the contact probe head.

By providing the reinforcing member in parts of the support member whereconductive contact members are relatively sparsely distributed or so asto surround each group of conductive contact members, it is possible toachieve a reinforcement which suits the particular layout of theconductive contact members. In particular, when a simple annularreinforcement member is used, the manufacturing cost can be particularlyreduced owing to the simplicity of the reinforcement member.

When the support member assembly is formed by laminating a plurality ofplate members, by reinforcing only the outer layer facing the object tobe contacted, the positional accuracy of the conductive contact membersof the contact probe head with respect to the objected to be contactedcan be increased without requiring any significant change in the designof the remaining part of the contact probe head. In this case, becausethe reinforcing member is needed only in the outer layer of thelaminated structure, the cost of the contact probe head suitable for awafer level burn-in test can be provided at low cost.

1. A support member assembly suitable for use in a contact probe head orthe like for contacting an object to be contacted, comprising: a supportmember formed with a plurality of holder holes for supporting conductivecontact members in a mutually parallel relationship, the support memberbeing made of material suitable for forming such holder holes; and areinforcing member integrally formed with the support member andextending in a part of the support member devoid of any holder holes. 2.A support member assembly according to claim 1, wherein the reinforcingmember divides the support member into a plurality of regions each ofwhich is formed with a plurality of holder holes.
 3. A support memberassembly according to claim 1, wherein the reinforcing member dividesthe support member into a plurality of regions each of which is formedwith a single holder hole.
 4. A support member assembly according toclaim 1, wherein the reinforcing member consists of an annular memberextending along an outer peripheral part of the support member.
 5. Asupport member assembly according to claim 1, wherein the reinforcingmember is buried in the support member.
 6. A support member assemblyaccording to claim 1, wherein the reinforcing member consists of a lowthermal expansion metallic member, and the support member is made ofplastic material.
 7. A support member assembly according to claim 6,wherein the reinforcing member is insert molded in the support member.8. A support member assembly according to claim 6, wherein thereinforcing member is externally attached to the support member.
 9. Asupport member assembly according to claim 1, wherein the support memberconsists of a first plate member, the assembly further comprising atleast a second plate member placed over the support member and providedwith holder holes aligning with the holders holes of the support member.10. A support member assembly according to claim 9, wherein the secondplate member is not incorporated with a reinforcing member.
 11. Asupport member assembly according to claim 9, wherein the second platemember is incorporated with a reinforcing member.
 12. A support memberassembly according to claim 9, wherein the reinforcing member comprisesa pair of annular members which clamp the plate members of the assemblytogether along an outer periphery thereof.